Control systems of certain guided missiles track the missile using infrared cameras having a sensor array that measures 480×120 pixels. The video information from this camera is fed to image processing hardware and software that uses various processing algorithms to extract information from the video input. Particularly, the video information is processed to determine the location of the missile by searching for the missile's thermal signature. Systems of this general type are used to track and guide TOW missiles. Because these systems are part of a servo control loop that controls the direction of the missile in flight, a very fast response from every component in the system is necessary.
Since the development of infrared cameras with 480×120 pixel arrays, newer cameras with more and smaller pixels have been developed. The advent of these newer, improved cameras has provided an opportunity to improve the accuracy of the information derived from the camera. Specifically, the newer cameras not only have larger arrays, but they are more sensitive and can detect images at a greater distance than the older infrared cameras. However, the substantial investment in hardware and software that processes the video information in the balance of the control system makes it advisable to retain those components unaltered. Therefore a method was sought to map the pixels of the newer camera (in this application called the “sensor array”) to the array of larger pixels of the processor (in this application called the “tracker array”).
A conventional method for converting a larger array of a camera or other sensor to a smaller one of a processor would be to accumulate an entire frame, for example, collect an odd scan then an even scan of an array, and then process the data in the frame, assigning each sensor pixel to the closest pixel of the coarser grid of the tracker array. The value assigned to some target pixels might be the weighted average of the closest sensor array pixels. Such a method works, but it requires time to accumulate a full frame of data before any further processing can take place. In the context of a missile controller where the data is used to direct a missile in flight such a lag is unacceptable. Accordingly, there is a need for a faster method to convert data from a fine array of a sensor to a courser tracker array. The present invention addresses that need.